Induction coil assembly for uterine ablation and method

ABSTRACT

A vapor delivery device includes an induction coil system. The induction coil system can include a coiled fluid tube, a coiled wire, a capsule between the coiled fluid tube and the wire, and a cooling fluid supply configured to force a cooling fluid through the capsule across the coiled wire. The induction coil system can include a closed loop ferrite core, a wire coiled around a first portion of the ferrite core, and a fluid tube coiled around a second portion of the ferrite core. A wire coil can be contained in a cartridge system removably coupleable to a disposable vapor delivery device. The system can include a fluid flow controller and induction power regulation to maintain a specific operating pressure range for vapor within a uterus or other bodily cavity, tract, or duct.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Application No.PCT/US2018/038626, filed Jun. 20, 2018, which claims priority to U.S.Provisional Application Nos. 62/642,245, filed Mar. 13, 2018;62/524,041, filed Jun. 23, 2017; and 62/522,091, filed Jun. 20, 2017,all of which are incorporated by reference herein in their entireties.

FIELD OF THE DISCLOSURE

The present disclosure relates to an induction coil and heating coil forproducing vapor for ablating tissue in medical applications.

BACKGROUND

Various methods and systems for generating steam or vapor for tissueablation for medical applications have been described. Some of thesemedical devices heat or vaporize water or saline, and deliver the heatedor vaporized fluid to a target tissue site by use of a cannula, needle,or other delivery instrument. As a byproduct of heating the fluid, powersupplied to these medical devices can generate heat in the device thatcan degrade performance of the induction coils or affect the handling ofthe device. Large insulation zones or air gaps can reduce the conductionof heat to the medical instrument, but add bulk and size to the deliveryinstrument which can be impactful for medical applications that requirea lower profile delivery to the target tissue.

As the length of tissue treatment increases, the problem of heataccumulation becomes more acute. In many cases, short time durations orbursts of vapor treatment have been effective for causing thermalnecrosis of tumors, fibroids, lesions of the lungs, prostate glands, andvaricose veins. These short durations can last 3 to 20 seconds, which issufficient time to provide thermal energy to ablate tissue at the depthappropriate for that particular application. For short time durations,the heat buildup in the inductive coil may be minimal.

Other thermal treatments require greater time durations to adequatelyablate tissue to an effective depth. As a representative example,uterine endometrial ablation requires approximate two minutes of vapordelivery to effectively treat the uterine cavity to a depth of ablationof 3 to 6 mm. In such applications, heat mitigation can be an importantdesign consideration.

SUMMARY

A hand held disposable device for treatment of abnormal uterine bleedingwhich incorporates an induction heating coil assembly that can reducecoil heating and power requirements in conjunction with a longertreatment cycle is disclosed. An active cooling mechanism configured toreduce heat buildup in the induction coil and reduce the size and bulkof the hand-held unit is described herein. The device can have asingle-use heating element which contacts and heats water or saline, anda multi-use driving coil. The device can have a closed loop ferrite coreto reduce excessive thermal buildup within the induction coil assembly.

A hand held disposable device for treatment of abnormal uterine bleedingwhich incorporates an induction heating coil configured to deliver vaporwithin the device for ablation of tissue is described. The device caninclude a single-use heating element which contacts and heats water orsaline, and a multi-use driving coil. Energy can be transferredinductively between the two coils. Treatment can be achieved bydelivering vapor to the uterine cavity within a prescribed pressurerange, typically about 50 mmHg, that is below the cracking pressure ofthe fallopian tubes, and for a period, typically about 2 minutes, thatis long enough to achieve an ablation depth that reaches the myometrium.

The device can have a magnetic core to increase the inductance andmagnetic coupling, for example, allowing flexibility to choose afrequency range that enables the induction coil configuration to be ofan appropriate size that fits within the physical constraints of thehandle of the medical device or delivery instrument, and to run at ahigher efficiency that reduces the amount of active cooling needed.

The device can have a coaxial and/or concentrically alignedconfiguration of the heating coil and induction coil. The heating coilscan be configured to run or be in loops. The heating coils can run or bepositioned in a back and forth orientation, up and down along theinduction coil to maximize the exposure to the magnetic field and vaporproduction time while maintaining a small profile.

For the magnetic core, material with a high magnetic permeability may beused to increase the efficiency and/or decrease the size of theinduction heating arrangement. The magnetic material can help containthe magnetic flux, reducing electromagnetic interference to othercomponents. The magnetic material may increase the magnetizinginductance, allowing efficient operation at lower frequencies. Themagnetic material can increase coupling, thereby reducing the voltageand/or current necessary to drive a load at a certain power. Increasedcoupling may also allow efficient operation without needing to drive thearrangement at resonance, thereby significantly increasing the range ofefficient driving frequency. If the arrangement is optionally driven ina resonant fashion, the higher inductance granted by the core can reducethe size of capacitors needed for resonance at a given frequency.

Because the magnetic material can increase the coil inductance, fewerturns of wire may be required. This may allow the use of a largerdiameter wire without increasing the size of the induction coilconfiguration, subsequently reducing the ohmic heating losses. Litz wiremay be appropriate for higher frequencies. The winding may be a singlelayer or it may be multiple layers thick to reduce the length of thearrangement as well as increase the inductance per turn.

The material may be chosen to have a high bulk resistivity (e.g.ferrite) to prevent current from circulating in the magnetic material.Alternatively, the magnetic material may be chosen to have a moderate orlow resistivity and act as the heating element itself (e.g. mu metal ormagnetic stainless steel).

The driving coil may be concentric with the heating coil/element(heating element is not necessarily a coil, but will be referred to asone here). In this case, the driving coil may be either the inner orouter coil. Alternatively, both coils may be around the magneticmaterial but not concentric with each other, as the magnetic materialcan conduct the magnetic flux between the two. This allows forarrangements where the coils are physically separated from each other toreduce heat conduction from the heating element to the driving coil, orto improve the physical mating operation between the two parts of aninduction coil system. The location and position of the driving coil,comprising a coiled fluid tube and a coiled wire. The coiled fluid tubecan be configured to carry a fluid, and the coiled wire can beconfigured to carry an electric current. The electric current in thecoiled wire can generate a magnetizing inductance to inductively heatthe coiled fluid tube. A capsule can separate items from the metallictubes for heating. This can be done for cost saving purposes by allowingthe driving coil to be configured as a re-usable or re-posable itemversus a disposable component of the system. The location of the drivingcoil can also influence the efficiency of the electric field, theinductive heating of the metallic tube, the resultant heat buildupwithin the system, and the quality of the vapor that is produced. Thedriving coil can also be in a closed loop configuration with a ferritecore material, the coiled fluid tube, and the coiled wire. A coolingfluid supply can force a cooling fluid, such as air, through the capsuleand across the coiled wire.

The magnetic material may take the form of a rod located concentricallywith the driving coil and the heating element. The magnetic material mayform a complete loop around both the driving coil and the heating coilto maximize coupling and magnetizing inductance. There may be one ormore gaps in the magnetic material to reduce volume and/or preventmagnetic saturation of the material and reduce core losses. Gaps can belocated near the middle of the driving coil to reduce their effect oncoupling. Gaps may reduce the effect of mechanical tolerances where twopieces of magnetic material meet.

The induction coil assemblies described herein with and without activecooling can provide consistent vapor delivery for uterine endometrialablation procedures without excessive thermal buildup and within theprescribed intrauterine pressure range.

A hand held disposable device configured to deliver vapor for ablationof tissue is described. The device can include an induction coil system,comprising a coiled fluid tube and a coiled wire. The coiled fluid tubecan be configured to carry a fluid, and the coiled wire can beconfigured to carry an electric current. The electric current in thecoiled wire can generate a magnetizing inductance to inductively heatthe coiled fluid tube. A capsule can separate the coiled fluid tube andthe coiled wire. A cooling fluid supply can force a cooling fluid, suchas air, through the capsule and across the coiled wire.

The disposable device can have an induction coil system comprising aclosed loop ferrite core. A wire configured to carry electric currentcan be coiled around a first portion of the closed loop ferrite core andat least partially surrounded by the closed loop ferrite core. A fluidtube configured to carry a fluid can be coiled around a second portionof the closed loop ferrite core and at least partially surrounded by theclosed loop ferrite core. Electric current in the wire can generate amagnetizing inductance to inductively heat the fluid tube.

The disposable device can have a cartridge system coupleable to thedisposable device. The cartridge system can include a connectorconfigured to removably couple the cartridge system to the disposablevapor delivery device. The cartridge system can further include a wirecoil configured to carry electric current, wherein the electric currentin the wire produces a magnetic field in at least a portion of thecoiled fluid tube when the cartridge system is coupled to the disposablevapor delivery device. A controller in the cartridge system can beconfigured to determine if the disposable vapor delivery device haspreviously been used. If the controller determines the device has notpreviously been used, the controller can provide the electric current tothe wire coil.

BRIEF DESCRIPTION OF FIGURES

FIG. 1 illustrates an example induction coil.

FIG. 2 illustrates an example closed loop induction coil.

FIG. 3 illustrates a cut-away view of an example vapor delivery device.

FIGS. 4a-4c illustrate an example vapor delivery device with a cartridgeassembly.

FIG. 5 is a graph illustrating an example relationship between wiretemperature and air flow rate.

FIG. 6 is a flowchart illustrating an example algorithm for a pressurecontrol system.

FIG. 7 illustrates a cross section of an example active air cooledinduction coil system.

FIG. 8 illustrates a cross section of another example active air cooledinduction coil system.

FIGS. 9A-9D illustrate an example active air cooled induction coilsystem.

FIGS. 10A-10E illustrate a capsule in an active air cooled inductioncoil system.

FIG. 11 illustrates that cooling air can flow transversely or laterallywithin the capsule.

FIGS. 12A and 12B illustrate example inductive coil assemblies includingclosed-loop ferrite cores.

FIGS. 13A-13B illustrate an example inductive coil module assembly withseparable bottom and top container halves.

FIGS. 14A-14B are cut away views of an example vapor delivery device.

FIG. 15 is a graph illustrating temperature and pressure in an inductioncoil assembly during a treatment cycle.

FIGS. 16A-16H illustrate example components of an inductive coil moduleassembly as they are assembled.

FIGS. 17A-17B illustrate an example closed-loop ferrite core.

FIG. 18 illustrates an example side cross section of an inductive coilmodule assembly.

FIG. 19 illustrates an example top view of an inductive coil moduleassembly.

FIG. 20 illustrates an example front view of an inductive coil moduleassembly.

FIG. 21 illustrates in cross-section an example of attachment mechanismsfacilitating assembly of a closed loop ferrite core.

FIGS. 22A-22B illustrate example configurations of a metallic tube forheating fluid in a vapor delivery device.

FIG. 23 illustrates an example vapor delivery device with a cartridgeassembly.

FIG. 24 illustrates an example lock tab for coupling a cartridgeassembly to a vapor delivery device.

FIG. 25 illustrates an example lock tab for coupling a cartridgeassembly to a vapor delivery device.

FIG. 26 illustrates a side view of a cartridge assembly.

FIG. 27 illustrates a memory in an example vapor delivery device.

FIG. 28 illustrates an example cartridge control procedure.

FIG. 29 illustrates an example system for damping pressure fluctuations.

FIGS. 30A-30B illustrate example chambers for damping pressurefluctuations.

DETAILED DESCRIPTION

FIG. 1 illustrates a cutaway view of an example induction coil 100 for avapor generator. The vapor generator and system can supply thermalenergy in vapor form to ablate tissue. Vapor can be used in the ablationof bodily cavities, vessels, or ducts in which the size, shape, andinterior morphology can vary from patient to patient. Vapor is amorphousand can conform to contact the interior surface of the bodily cavity toeffect ablation. One application is the ablation of endometrium forwomen with abnormal bleeding. Other applications include the gallbladder, or other cavities or lumens. The application for vapor caninclude tissue masses, tumors, or targeted tissue such as nerve, muscle,arterial, or venous vessels. The induction coil 100 can be configured togenerate a high quality heated condensable vapor for any of theseapplications.

The vapor generator induction coil 100 can include an outer assembly 104and an inner assembly 106 disposed within the outer assembly 104. Theouter assembly 104 can be thermally insulating to reduce thermal damageto components of the induction coil 100 or transfer of excessive heat toan operator or patient. To thermally insulate the induction coil 100,the outer assembly 104 can comprise a material with a low thermalconductivity such as aerogel, foam, fiberglass, or low-density silicone.The outer assembly 104 can additionally or alternatively contain airgaps. In addition to being thermally insulating, the outer assembly 104can be electrically insulating.

A wire 102 can be coiled around the outer assembly 104. The wire 102,which can comprise a Litz wire, an insulated wire, or a coiled magnetwire, can be coupled to an RF generator that can produce a current inthe coiled wire 102 to generate an inductive electromagnetic field. Thewire 102 can be wrapped around the outer assembly 104 for a specifiednumber of turns or wraps. The number of wraps can depend on parametersof the application, including power requirements and gauge of the wire102. The number of wraps can be low in number, for example 2, 3, or 4complete (360 degree) wraps around the outer assembly 104, or can behigher numbers of wraps such as 30, 300, or 3000. The wire 102 can havea diameter between approximately 10 AWG and 20 AWG. For example, theouter assembly 104 can be wrapped by a wire 102 having a diameter of 16AWG and approximately ten complete turns.

The inner assembly 106 can be electrically insulating and thermallyconductive. For example, the inner assembly 106 can comprise a materialsuch as aluminum nitride, alloys of iron including stainless steels,alloys of nickel including ferrite, alloys of cobalt, quartz, glass, ora ceramic such as aluminum oxide.

One or more metallic tubes 108 can be supported by the inner assembly106. The tubes 108 can comprise a single tube that is wrapped around theinner assembly 106, and is also referred to herein as a “heating coil.”The metallic tubes 108 can alternatively comprise an array of 10 tubesto 250 or more metallic microtubes, aligned in a parallel array. The oneor more tubes 108 may have outside diameters ranging from 0.5 mm to 2.5mm, and inside diameters in the range of 0.25 to 2 mm. The metallictubes 108 can have magnetic permeability larger than 1.5 at theoperating frequency of the generator. The tubes 108 may be bundledtogether, for example tightly enough so that there is physical contactbetween adjacent tubes 108. They may be physically joined with ametallic material such as solder, welds, mechanical joints, or the tubesmay be holes drilled longitudinally through the length of a solidmetallic rod.

The metallic tubes 108 can be coupled to a fluid source 118 supplyingsaline, water, distilled water, or other fluid to be heated or convertedinto steam or vapor in the tubes 108. The metallic tubes 108 and thefluid can be inductively heated by the inductive electromagnetic fieldgenerated by current in the coiled wire 102.

FIG. 2 illustrates a closed loop ferrite induction coil system 200 thatcan be used to treat fluid within a pipe to reduce scaling in the fluid.The closed loop ferrite induction coil system 200 can include a closedloop ferrite ring 210 and a pipe 220. An insulated wire 230 can bewrapped around the closed loop ferrite ring 210 coupled to a RF powersource 240, which can provide an alternating electrical current tocreate a magnetic field. Pipe 220 can contain fluid 250. The magneticfield generated by the current in the ferrite ring 210 can heat the pipe220 and the fluid 250 by inductive heating. The closed loop ferriteassembly can reduce stray currents and thermal build up in the insulatedwire 230 wrapping the ferrite ring 210.

FIG. 3 illustrates a cut-away view of an example vapor delivery device300 including an induction coil assembly 310. The vapor delivery device300 can be used, for example, for uterine endometrial ablationprocedures. A user, such as a physician, can hold the vapor deliverydevice 300 by handle 330. Connections, conduits, and tubing to thecontroller and fluid supply (not shown in FIG. 3) can be providedthrough a connector 360 at the proximal end 362 of the vapor deliverydevice 300.

Fluid such as saline, water, or distilled water can be supplied to thevapor delivery device 300 through a fluid conduit 320. The inductioncoil assembly 310 can heat or vaporize the fluid entering the conduit320. For example, the fluid can pass through the induction coil assembly310, where a magnetic field generated by an alternating current in aninsulated or Litz wire can heat or vaporize the fluid by inductiveheating. The heated or vaporized fluid can be delivered through a distalend 350 to a target tissue site of the patient. Vapor delivery devicecan contain pressure sensors and pressure relief valves (not shown) toregulate the amount of vapor delivered to the bodily cavity

FIGS. 4A through 4C show one example configuration of the vapor deliverydevice 300 and induction coil assembly 310. FIG. 4A shows one-half ofthe vapor delivery device 300 to illustrate the internal components ofthe device. The vapor delivery device 300 can have a handle 330 that canbe manually grasped by the physician. At the proximal end of the handle330 can be proximal opening 422 containing the fluid conduit 320. Thedistal end 350 of the vapor delivery device 300 can have an opening toprovide vapor or heated fluid, or non-heated fluid or media to thetarget tissue site.

The fluid conduit 320 can provide a pathway for fluid to flow throughthe handle 330 and into the metallic tube 440. The fluid can be heatedor vaporized in the metallic tube 440 when RF power is delivered, andthe heated or vaporized fluid can enter the vapor input port 414 to bedelivered to a target tissue site through distal end 350. Located nearthe distal end 350 of the vapor delivery device 300 can be a pressuresensor 451 and sealing balloons 452. The pressure sensor 451 can measurea pressure of a body cavity, such as an intrauterine pressure, and thesealing balloons 452 can interact with the endocervical canal once thedistal end 350 has been inserted within the patient. For example, thesealing balloons 452 can inflate against the walls of the endocervicalcanal to stabilize the device and insulate. Air supply conduits withinvapor delivery device provide pressurized air from an air supply sourceto inflate the sealing balloons 452 to occlude the endocervical canal.

Any fluid pathways that deliver fluid or vapor to the patient, as wellas any portions of the device 300 that may contact the patient, can becontained in a disposable portion. A cartridge assembly 412, which canbe a reusable or reposable instrument, can couple with the disposableportion to form the vapor delivery device 300. The cartridge assembly412 can include an inductive coil 432 that, together with the metallictube 440, forms the induction coil assembly 310. When the cartridgeassembly 412 is coupled to the disposable portion, current in theinductive coil 432 can inductively heat the metallic tube 440. Forexample, the cartridge assembly 412 can have an induction coil opening418 that is designed to accept the metallic tube 440. When the cartridgeassembly 412 is coupled with the disposable portion, the metallic tube440 can fit within the induction coil opening 418 such that the metallictube 440 at least partially overlaps the inductive coil 432 and resideswithin a magnetic field created by current in the inductive coil 432.

The cartridge assembly 412 can also include pneumatic valves 480, whichcan control fluid delivery for integrity tests or enhancing ultrasonicvisualization of a bodily cavity. For example, the pneumatic valves 480can aid in an integrity test to verify that a uterine cavity is intactand ready for ablation. A connection 360 can couple the cartridgeassembly 412 to a controller (not shown). The connection 360 can containan electrical connection for the inductive coil 432, air supply conduitsfor balloons 452, air cooling conduits to facilitate reducing excessivethermal effects within the handle 330 and the inductive coil 432, aconnection for thermocouples for the inductive coil 432, a connectionfor a thermocouple in a portion of the vapor delivery device 300 thatmay contact a patient, a connection to pneumatic valves 480 that controlfluid delivery for integrity tests to verify that the uterine cavity isintact and ready for vapor delivery, and/or a connection for thepressure sensor 451. These connections can couple correspondingcomponents to the controller for processing, monitoring, and display bythe controller hardware and software.

To use the vapor delivery device 300, a physician can insert thecartridge assembly 412 into the disposable portion. FIG. 4b demonstratesan example of the cartridge assembly 412 shown in FIG. 4a being insertedinto vapor delivery device 300 but not yet fully coupled. In FIG. 4b ,the cartridge assembly 412 can be inserted within proximal opening 422of the handle 330 of the vapor delivery device 300.

FIG. 4c shows an example of the cartridge assembly 412 fully engagedwithin the vapor delivery device 300. Upon engagement, connections tothermocouples, intrauterine pressure sensors, electrical current fromthe controller, and air supply conduits can be completed. Fluid can thensupplied through fluid conduit 320 to the metallic tube 440, where thefluid can be heated or vaporized when the induction coil 432 is poweredand regulated via the controller.

The controller can also regulate vapor delivery to a target tissue siteby the vapor delivery device 300. For the uterine endometrial ablationapplication, vapor delivery into the uterus can be monitored to avoidvapor escaping from the uterus via the fallopian tubes or theendocervical canal. As an example, high intrauterine vapor pressures cancause vapor to traverse the length of the fallopian tubes or causethermal injury through the fallopian tube wall, potentially damagingorgans in the peritoneal cavity. The medical literature reports theaverage cracking pressure of fallopian tubes in women as 70 mmHg. Thecontroller may therefore monitor the intrauterine pressure using thepressure sensors 451 and regulate the intrauterine pressure below 70mmHg during the treatment procedure. In addition, the controller maymonitor for sudden drops in intrauterine pressure or rapid increases invapor flow, which may be indicative that a seal of endocervical canalhas failed.

The controller can also monitor temperature of the inductive coilassembly 310. Excessive heat build-up can damage the inductive coil 432or the vapor delivery device 300 itself. Excessive heat build-up canalso create safety issues. For the operator, the inductive coil assembly310 may be positioned in the handle held by the hand of the operator.For the patient, the vapor delivery device may be in close proximity tosensitive tissue, such as the patient's pelvic region, vagina, andcervix. In both situations, excessive heat build-up in the inductivecoil assembly 310 can produce unintended thermal injury. Especially forprocedures involving greater depths of ablation and large treatmentareas, thermal build-up in the inductive coil assembly 310 can beproblematic.

Active Air-Cooled Induction Coil System

To address heat build-up in the inductive coil assembly 310, theinductive coil assembly 310 can be insulated by foam, silicone, rubber,plastic, and/or air gaps. However, these layers of insulation and airgaps may lead to larger and heavier vapor delivery devices. For vapordelivery devices that are hand-held or designed to be used in aminimally invasive manner through a small portal into the patient'sbody, the size and weight of the device may significantly constrain itsdesign. Accordingly, the vapor delivery device 300 may employ activecooling to provide for heat mitigation without a significant increase tothe size or weight of the device.

Referring back to FIG. 4c , connection 360 can contain an air conduitthat is designed to force air driven by an air pump in the controller(not shown) onto or into the inductive coil assembly 310. A portion ofthe heat generated in the inductive coil assembly 310 can be transferredto the air as it is forced past the Litz wire 432, cooling the inductivecoil assembly 310. The data in Table 1 below and Graph 1 in FIG. 5demonstrate the benefit of air cooling system on the inductive coilassembly.

TABLE 1 Airflow versus Wire Temperature in Inductive Coil AssemblySteady state runs done at 95% vapor quality and 360 watts. Air Flow(cfm) Thermocouple 3 temperature 0.5 149 0.66 138 0.83 132 1 118

The data in Table 1 above and in Graph 1 in FIG. 5 illustrate a decreasein temperature of the Litz wire 432 corresponding to an increased rateof air flow. Accordingly, forcing air across the Litz wire 432 canbeneficially mitigate heat build-up in the inductive coil assembly 310.The rate of air flow across the Litz wire 432 can be adjusted based on adesired wire temperature.

FIG. 6 illustrates an algorithm of a pressure control system for aninductive coil that can be used for vapor delivery in the uterinecavity. Once the vapor delivery device has had the requiredpre-procedure checks, endocervical sealing steps, safety tests, deviceinsertion, and final device positioning and placement into the uterinecavity, the treatment can be ready to begin 602. Vapor can be producedby saline, water, or other fluid being driven into the metallic tube ofthe vapor delivery device 300. Simultaneously, or within a prescribedsoftware and hardware driven fashion, electrical current from the RFpower source can be provided to the inductive coil 432 in the inductivecoil assembly 310. The resultant magnetic field can heat the metallictube to heat the fluid. The flow of fluid into the metallic tube can becontrolled by a stepper motor on a syringe pump, or a peristaltic pump,or other fluid flow or pressure controlled system. Within the vapordelivery device, an intrauterine pressure sensor 451 can monitor 604 thepressure of the vapor in the uterine cavity. A target range ofintrauterine pressures can be between 20 to 60 mmHg, or 20 to 52 mmHg,or within a range of 48 to 52 mmHg. The pressure control system can beresponsive to rapid changes in the intrauterine pressure. For example,the intrauterine pressure can change rapidly as a result of uterinecontractions, condensation of the vapor, residual fluid, tissue, loosetissue, blood in the uterine cavity, and the outflow of fluid andmaterial from the uterine cavity. The vapor delivery device can have ininflow of vapor at its distal end and an outflow conduit that can allowexcess fluid, vapor, and uterine materials to exit out of the uterus asa continuous inflow/outflow system. The continuous inflow/outflow systemprovides for the continual inflow of vapor that can condense on the wallof the uterine cavity. However, this system and other systems used forother bodily cavities, lumens, or target tissues can have only asingular inflow port for the delivery of vapor.

Referring back to FIG. 6, the stepper motor can be controlled andmonitored to drive 606 saline to the inductive coil assembly 310. Thepower supply can drive 608 current to the inductive coil 432 to heat themetallic tube 440 and produce 610 vapor. The resultant intrauterinepressure can be monitored 612 and feedback provided to the uterinecavity algorithm to maintain a targeted intrauterine pressure rangebetween, e.g., 48 and 52 mmHg. During the treatment, the temperature ofthe inductive coil assembly can be monitored 614 to verify that a safeand proper operative range is maintained. The safe and propertemperature can be dynamically controlled by the active cooling 1232 ofthe inductive coil assembly. A temperature that exceeds or becomesoutside the expected range can serve to produce an error condition thatwill terminate the vapor treatment procedure. In addition, thermocouplescan be placed on one or both of the inductive coil 432 and the metallictube 440 during the treatment cycle. Active cooling can also serve toregulate the temperature of the metallic tube 440 to facilitate controlof the temperature of the inductive coil assembly and the ultimatetemperature of the metallic tubes to control the vapor quality, vaporpressure, and vapor temperature.

The system described in FIG. 6 can continue the vapor treatment usingthe intrauterine pressure control system until a procedure timer reachesits prescribed time limit 618. Alternatively or in addition, thetreatment can be constructed to terminate once a certain intrauterinetemperature is achieved, a pre-determined flow or volume of vapor isreached, or the monitoring of the outflow temperature or constituentsreach a certain level, or combinations of the above to provide either apredetermine ablation treatment or a patient tailored, prescribedablation treatment level is achieved.

FIG. 7 shows a cross section of an example active air cooled inductioncoil system 700. In the active air cooled induction coil system 700,coils of a Litz wire 710 can be wrapped concentric to a heating coil720. Cooling assembly 700 contains conduits for air flow seen exitingair cooling ports 730 and around Litz wire 710 within the coolingassembly. The heating coil 720 can be made from Inconel, stainlesssteel, or other ferromagnetic material, and can contain the fluid to beheated or vaporized. The Litz wire 710 can be connected to an RF powersource and controller (not shown). Current in the Litz wire 710 can beused to heat the fluid in the heating coil 720 via inductive heating.

The cooling assembly 700 can also include air cooling ports 730. Air canbe delivered to and forced through the air cooling ports 730 by conduitsconnected to an air source and a controller (not shown). The air fromthe air cooling ports 730 can be forced across the heating coil 720and/or the Litz wire 710, dissipating heat from the cooling assembly700.

FIG. 8 shows a cross section of another example active air cooledinduction coil system 700. As shown in FIG. 8, the coil system 700 caninclude a capsule 810, which can be made from a dielectric material suchas ceramic, glass, mica, polysulfone, or Ultem. A heating coil 720containing a fluid can be external to the capsule 810. A Litz wire 710can be coiled within the capsule 810, concentric to a ferrite core 820and within an air chamber 830. Circulating air can enter the air chamber830 via an air input port 832, which can be connected to a conduit andan air source driven by a controller (not shown). The circulating aircan be forced through the air chamber 830 to outflow exits 834 toactively cool the Litz wire 710.

The Litz coil 710 can be cooled with two fluids. For example, the Litzcoil 710 can be cooled by air flowing through the air chamber 830 and bysaline or water flowing through the heating coil 720. The fluid enteringthe heating coil 720 and/or the air entering the air input port 832 canbe at about room temperature (e.g., about 70 to 75° F.), or about 100°F., for example due to pre-heating of the air and or water by thermalconduction via the outbound water and/or air.

The Litz coil 710 can use 500 W initially for about 30 seconds (e.g., 10to 50 seconds, more narrowly 20 to 40 seconds) and then 350 W electricalpower for about 110 seconds into the Litz coils during use. The totaltreatment time can be about 110 seconds to about 170 seconds, forexample 140 seconds total. During a single treatment or use, the Litzcoil can use about 21 to about 27 kJ, for example about 24 kJ, forexample over about 140 seconds.

FIGS. 9A-9D show photographs of the example active air cooled inductioncoil system 700. In FIG. 9A, the capsule 810 is seen with Litz wire 710that can be connected to an RF power source and a controller (notshown). Alongside Litz wire 710 in FIG. 9A is a wire thermocouple 910,which can provide temperature monitoring of the induction coil system700. Within the capsule 810, the Litz wire 710 can be wound around theferrite core 820 (not visible) to form a coil. Circulating air from anair source and controller can be connected to the air input port 832.Air can enter the capsule 810 via the air input port 832 and exit thecapsule 810 at air outflow exits 834, cooling the Litz wire 710 withinair chamber 830 as the air is forced through the capsule 810.

FIG. 9B shows a photograph of an example heating coil 720 with athermocouple wire 920 and heating coil wraps 930. Fluid can enter theheating coil 720 via a fluid input 942 and wind through multiple wraps930, which can be held in place by solder or weld joints 932. The fluidcan be heated or vaporized as it passes through the wraps 930, and theheated or vaporized fluid can be delivered to a vapor delivery devicevia a fluid output 944.

Each wrap 930 and solder joint 932 shown in FIG. 9B can create anelectrical single turn. Six full (360°) turns are illustrated in FIG. 9Bwithin the single fluidic pathway with fluid input tube 942 and vaporoutput tube 944, but the heating coil 720 may have more or less than sixfull turns.

With the desire to keep the induction coil system 700 small while alsoefficient to reduce heating the Litz wire 710 and ferrite core 820,design considerations for elements of the induction coil system 700 mayinclude magnetizing and leakage inductance, load resistance, turns ratiobetween the Litz wire 710 and heating coil 720, diameter of the Litzwire 710, and the volume and shape of the ferrite core 820. The numberof turns, length of turns, cross-sectional area and resistivity of thematerial in the heating coil 720 may affect a load resistance, which canbe matched, via a turns ratio to the Litz wire 710, to a load resistancethat is practical to drive using the RF power supply and cable.

FIG. 9C shows an example of the capsule 810 and heating coil 720 priorto final assembly, while FIG. 9D shows the capsule 810 insertconcentrically within the heating coil 720 to complete the active aircooled induction coil system 700. Final assembly can be performed in themanufacturing process or as the components are assembled by the enduser. As an example, capsule 810 can be configured as a reusablecomponent that is inserted into a disposable vapor delivery deviceincluding the heating coil 720. The capsule 810 can be reused formultiple procedures, while the heating coil 720 and other components ofthe disposable vapor delivery device can be disposed after eachprocedure.

FIGS. 10A-10G illustrate different views of a variation of the capsule810.

FIGS. 10A-10G illustrate that the capsule 810 can include multiple ports1012 facilitating air flow into the capsule 810 or air flow out of thecapsule 810. As shown in FIG. 10B, the ports 1012 can be at equal radiias each other (i.e., the other ports 1012 can be at the same radii aseach other). As shown in FIG. 10C, the ports 1012 can be at evenlydistributed angles 1016 as each other from a longitudinal axis 1018 ofthe capsule 810 (e.g., eight ports spread angularly at 0, 45, 90, 135,180, 225, 270, 315, and 360 degrees, respectively, about thelongitudinal axis 1018).

The ports 1012 can be at unequal radii to each other, and can be atunevenly distributed angles from the longitudinal axis 1018 of thecapsule as each other.

FIGS. 10B, 10D, and 10E illustrate bores or grooves 1014 on an innersurface of the capsule 810. The bores or grooves can be material absentduring molding of the capsule and/or can be material removed from thecapsule by milling or drilling. The bores 1014 can extend from aproximal terminal end of the capsule to a distal terminal end of thecapsule. The bores can longitudinally extend at least the correspondinglength of the Litz coil. The bores 1014 and the ports 1012 can togetherform a plurality of airflow channels through the capsule 810.

FIG. 11 illustrates that cooling air can flow transversely or laterallywithin the capsule. Cooling air can flow along the length of the Litzcoil 710, and/or between the windings of the Litz coil 710, eitherbetween windings that are spaced before air is blown between them and/orwindings in contact with each other before air blows between them.

Closed-Loop Ferrite Core Inductive Coil Assembly

FIG. 12A illustrates an alternate ferrite core, inductive coil assembly1200. In the inductive coil assembly 1200, a ferrite core 1210 can beconfigured in a closed loop, circular configuration. The closed loop canbe circular, elliptical, square, rectangular, or other multi-sidedgeometric configuration. Fluid can flow into the inductive coil assembly1200 via a metallic tube 1220. Metallic tube 1220 is shown in FIG. 12Awith one wrap 1222 around ferrite core 1210, but may instead havemultiple wraps around, within, along-side, or tangential to the ferritecore, or combinations thereof. An insulated wire 1230 is shown in FIG.12A with multiple wraps 1232 around the ferrite core 1210. The insulatedwire 1230 can be Litz, magnetic, or other wire source that is suppliedwith electrical current from the RF power source (not shown). Wraps 1232can be configured around, within, or tangential to the ferrite core1210. Wraps 1232 can be configured as a singular wrap or multiple wraps.The closed loop ferrite core 1210, by its configuration, can reducestray currents and heat accumulation in the insulated wire 1230.

FIG. 12B illustrates that the inductive coil assembly 1200 can have aclosed loop, ferrite core 1210, or combinations thereof. The ferritecore 1210 can be substantially rectangular in shape, substantiallyround, or have another multi-sided geometry. A metallic tube 1220configured to carry fluid can be wrapped one or more times around a sideof the ferrite core 1210. The metallic tube 1220 can have an input port1224 at one end that supplies fluid to the inductive coil assembly 1200and an output port 1226 that delivers the heated fluid or vapor to thedelivery device (not shown) at the other end. The metallic tube 1220 caninclude one or more wraps 1222 around the ferrite core 1210. Althoughthe wraps 1222 are shown on one side of the ferrite core 1210 in FIG.12B, the wraps 1222 can be configured on multiple sides and throughoutthe ferrite core 1210, or can be configured tangentially to or alongsidethe ferrite core 1210.

The inductive coil assembly 1200 can also include a Litz wire 615configured to carry electrical current from an RF power source (notshown). Litz wire 615 can have one or more wire wraps 1232 around a sideof the ferrite core 1210. Wire wraps 1232 can be configured on multiplesides and throughout the ferrite core 1210. Current in the wire wraps1232 can generate a magnetizing inductance to heat and/or vaporize fluidin the metallic tube 1220.

The ferrite core 1210 can be provided in multiple pieces that are placedtogether by the end user or in manufacturing. In FIG. 12B, dotted line1240 represents a potential splitting point for the closed loop, ferritecore 1210. Components to the left of the dotted line 1240 can bereusable components, while those on the right side of the dotted line1240 can be disposable. For example, the components to the left of thedotted line 1240 can be placed in a cartridge configured to fit into adisposable vapor delivery device. During use, a physician can insert thecartridge into the vapor delivery device to couple with the componentsto the right side of the dotted line 1240. The coupling engagement canbe facilitated by the left and right sides of the ferrite core 1210being pressed together by cams, friction fit, tongue and grooveengagement, or other mechanical detents that allow the two sides of theferrite core 1210 to couple sufficiently to complete the inductive coilassembly 1200, as shown in FIG. 12B, within the vapor delivery device.

The ferrite core 1210 can be separable in manners other than that shownin FIG. 12B to facilitate manufacturing or the vapor delivery deviceconfiguration. FIG. 12B illustrates splitting the ferrite core 1210 intotwo pieces, but the ferrite core 1210 can come in multiple pieces (i.e.greater than 2) depending upon the assembly technique and configurationof the desired magnetic field. As an example, the ferrite core 1210 canhave coupleable top and bottom halves each including ferrite sidepanels, ferrite front and back panels, central ferrite cores, oradditional ferrite cores for mounting the metallic heating tube 1220 andinsulated or Litz wire 615.

FIG. 13A shows an example inductive coil module assembly 1200 withseparable bottom and top container halves 1310 and 1315. When coupled,the bottom and top container halves 1310 and 1315 can encase the entireinductive coil assembly 700. Inductive coil support frame 1318 canreside within container halves 1310 and 1315 and hold separable piecesof a closed loop ferrite core 1320 together. The inductive coil supportframe 1318 can be made from heat shrink tubing that holds the pieces ofthe ferrite core 1320 together for electrical coupling.

The inductive coil module assembly 1200 can include an insulated wire1330 configured to carry an electric current, a metallic tube 1340configured to carry a fluid, and a thermocouple wire 1350. The insulatedwire 1330 and metallic tube 1340 can each be coiled around a portion ofthe ferrite core 1320. Electric current in the insulated wire 1330 cangenerate a magnetizing inductance to heat the metallic tube 1340. Themetallic tube 1340 can include an input 1342 providing fluid into theinductive coil module assembly 1200 and an output 1344 delivering vaporand/or heated fluid to a patient. The thermocouple wire 1350 can be usedto measure temperature within the inductive coil module assembly 1200during treatment.

The inductive coil support frame 1318 and container halves 1310 and 1315can include openings to allow a thermocouple wire 1350, insulated wires1330, input metallic tube 1342, and metallic vapor output tube 1344 toexit the inductive coil module assembly 1200.

FIG. 13B shows the inductive coil module assembly 1200 within bottomcontainer half 1315 alongside a vapor delivery device 1360. The vapordelivery device 1360 can include the top container half 1310, and thebottom container half 1315 can be configured to fit into the vapordelivery device 1360 to couple with the top container half 1310. Whenplaced within the vapor delivery device 1360, the inductive coil moduleassembly 1200 can reside at location 1362 above a handle 1364, which canbe used by a user to hold the device 1360. The vapor delivery device1360 can have a distal end 1366 where vapor generated in the inductivecoil module assembly 1200 exits the device and enters a patient.

FIG. 14A illustrates a cut away side view of an example vapor deliverydevice 1360 with handle 1364. Within the handle 1364 is handle hole 1402that can accept a cartridge and connections to controller (not shown). Aclosed loop ferrite core induction coil system 1410 can be containedwith the vapor delivery device 1360, and can be coupleable to an RFpower source via electrical connectors 1404.

FIG. 14B illustrates an example cut away axial view of the vapordelivery device 1200 with induction coil system 1410. The induction coilsystem 1410 can include closed loop ferrite core 1320 with heating coil1340 wrapped around a first part of the core 1320 and Litz wire 1330wrapped around a second part of the core 1320. Current in the Litz wire1330 can generate a magnetizing inductance to inductively heat theheating coil 1340.

Graph 2 in FIG. 15 illustrates that the induction coil assembly 1200with a closed loop ferrite core can reduce thermal buildup. In theexperiment represented in Graph 2, the induction coil assembly producedvapor for a time duration of 140 seconds (as shown on the X axis), forexample to perform uterine endometrial ablation. The Handle Temp lineshows a temperature of the handle 1364 measured by a thermocouple duringthe ablation treatment cycle. In the example of Graph 2, the temperaturegradually rises to 38° C. during the treatment cycle to the 140 secondmark at the end of the treatment cycle. The handle temperature continuesto rise in this experiment when the fluid delivery is terminated in thehandle and plateaus slightly above 45° C. The handle temperature may beregulated to stay below 48° C., the temperature set by the IEC 60601standard for a two minute exposure duration to skin or tissue forthermal necrosis.

The Pressure line in Graph 2 illustrates example pressure regulationduring the treatment cycle within a Pressure Max and Pressure Min range.This pressure range can be defined for the procedure performed using thevapor delivery device. For example, pressure for a uterine endometrialablation procedure may have a pressure max of 70 mmHg to reduce thepossibility of vapor entering or traversing the fallopian tubes. Thepressure min for the endometrial ablation procedure may be 20 mmHg toprovide enough distension pressure to expose the interior of the uterinecavity to vapor. The pressure may be regulated to approximately 48 mmHg,for example. The fluctuations of pressure shown in Graph 2 reflect thedynamic environment of the uterine cavity, the condensation of vapor asit contacts the interior wall, and the continuous flow configuration ofthe vapor delivery device with return lumen and outflow conduit. Graph 2illustrates that the pressure regulation system of the vapor deliverydevice can rapidly respond to the constantly changing intrauterinepressure environment and can regulate the pressure within a specifiedpressure range.

FIGS. 16A-16H illustrate example components of the inductive coil moduleassembly 1200 as they are assembled.

FIG. 16A shows the metallic tube 1340 with input 1342 and output 1344.The metal tube 1340 can be constructed from stainless steel, Inconel, orother metal as described earlier. Metallic tube 1340 can be configuredwith a loop 1602 and the input 1342 and output 1344 adjacent to or incontact with one another. An insulating tube cover 1610, constructedfrom Teflon, silicone, rubber, or other thermal insulator, can encloseat least part of the metal tube 1340.

The metal tube 1340 can be wrapped or bent, for example at bend 1604,around a bobbin 1620. As shown in FIG. 16A, the bobbin 1620 can beconfigured as a dowel, bobbin, or tube. The bobbin 1620 can comprise amaterial with a low electrical conductivity. The bobbin 1620 can alsohave a low thermal conductivity. For example, the bobbin 1620 can bemade from glass, ceramic, mica, or plastics such as polysulfone orUltem. The bobbin 1620 can aid manufacturing of the inductive coilassembly 1200.

FIG. 16B shows the metallic tube 1340 with bend 1604 wrapped around thebobbin 1620, which together can fit within a bottom half 1632 of theclosed loop ferrite core 1320.

FIG. 16C shows a ferrite closed loop top half 1634, which can be placedabove the matching ferrite closed loop bottom half 1632 to complete theclosed loop.

FIG. 16D shows the insulated wire 1330 can also be coiled around thebobbin 1620. The insulated wire 1330 can be coiled multiple times aroundthe bobbin 1620 and the metallic tube 1340 can be bent or coiled aroundthe bobbin 1620 outside and concentric to the insulated wire 1330. Themetallic tube 1340 can alternatively be placed between the bobbin 1620and the insulated wire 1330. FIG. 16D also shows that an input port 1642can be coupled to the input 1342 of the metallic tube 1340 and an outputport 1644 can be coupled to the output tube 1344.

FIGS. 16C-16D further illustrate that a closed loop ferrite core in theshape of a box can be formed by the top half 1634 and the bottom half1632. The box can include one or more of a left side 1652, a right side1654, a back side 1656, a top side 1658, and a bottom side 1660 composedof ferrite and formed integrally or connected in an abuttingconfiguration. FIG. BB3C shows that the top half 1634 and bottom half1632 when coupled can form a shape approximating a rectangular prism,where each of the left and right sides 1652 and 1654, back side, topside 1658, and bottom side 1660 are substantially rectangular in shape.The box can alternatively approximate a cylinder, where the top side1658 and bottom side 1660 are substantially circular in shape and one ormore rectangular sides couple the top and bottom. The ferrite core canapproximate other shapes, such as a sphere, a toroid, or an ellipsoid.The box formed by coupling the top half 1634 to the bottom half 1632 maybe integrally formed, separable, or releasably coupleable. Furthermore,the box can be constructed from more than two ferrite pieces.

When coupled, the top half 1634 and bottom half 1632 can provide anopening 1662 allowing the insulated wire 1330 and metallic tube 1340 toenter and exit the box. The top half 1634 and bottom half 1632 canprovide more than one opening. For example, the metallic tube 1340 andinsulated wire 1330 can enter the box through a first opening and exitthe box through a second opening, or the metallic tube 1340 can enterand exit the box through the first opening and the insulated wire 1330can enter and exit the box through the second opening. As anotherexample, the box can include a first opening through which the metallictube 1340 enters the box, a second opening through which the metallictube 1340 exits the box, a third opening through which the insulatedwire 1330 enters the box, and a fourth opening through which theinsulated wire 1330 exits the box.

Each of the top half 1634 and bottom half 1632 can include a ferritecenter 1664. The ferrite center 1664 can be formed integrally with thesides, top, and/or bottom of the box, or can directly contact or abutone or more of the sides, top, or bottom. The central pin may bepositioned at approximately a center of the ferrite core when the tophalf 1634 is coupled to the bottom half 1632.

FIG. 16E illustrates that the bobbin 1620, with metallic tube 1340 andinsulated wire 1330, can be enclosed within the closed loop ferrite coreformed by coupling the ferrite closed loop bottom half 1634 to theferrite closed loop top half 1634.

FIGS. 16F-16G show the inductive coil support frame 1318 can beassembled by wrapping the ferrite closed loop bottom half 1632 and tophalf 1634 in a heat shrink tubing. The ferrite core halves 1632 and 1634can be mechanically pressed together by the heat shrink 1318. Thecompletion of the magnetic field of multiple pieces of a ferrite corecan be accomplished with mechanical cams that physically press theferrite core pieces together without the use of heat shrink 1318.

FIG. 16H shows an example of the inductive coil module assembly 1200enclosed within the combined bottom and top container halves 1310 and1315, with thermocouple wire 1670, metallic tube input 1342, metallictube output 1344, and insulating wire 1330 exiting through a hole 1680.

FIGS. 17A-17B illustrate another example closed-loop ferrite core 1320.The ferrite core 1320 can have a substantially open shape surrounding aportion of the metallic tube 1330 and insulated wire 1340. As shown inFIG. 17B, the core can include a left side 1652, a right side 1654, atop side 1658, and a bottom side 1660, with open back and front sides.The left side 1652, right side 1654, top side 1658, and bottom side 1660may each be substantially rectangular in shape, or may be formed toapproximate other shapes. For example, the ferrite core 1320 maycomprise a toroidal or circular shape. The metallic tube 1330 andinsulated wire 1340 can be coiled around a ferrite center 1664 couplingthe top side 1658 to the bottom side 1660.

One or more wraps of each of the metallic tube 1340 and insulated wire1330 can be enclosed within or surrounded by the ferrite core 1320. Eachof the one or more wraps can wrap concentrically to the ferrite center1664. Each wrap may be an arc of less than 360 degrees (e.g., 180degree), or may be a closed 360-degree arc. FIG. 18 illustrates anexample side cross section of the metallic tube 1340 and insulated wire1330 wrapped a plurality of times and concentrically around the ferritecenter 1664, with the insulated wire 1330 wrapped adjacent to thecentral pin 1110 and the metallic tube 1340 wrapped concentrically tothe insulated wire 1330 and outside the insulated wire 1330. Theinsulated wire 1330 can be wrapped outside the metallic tube 1340. Thetop 1658 of the ferrite core 1320 can be formed integrally with the leftand right sides 1652 and 1654, bottom 1660, and ferrite center 1664, orcan be connected to the sides 1652 and 1654, bottom 1660, and ferritecenter 1664 after the metallic tube 1340 and insulated wire 1330 havebeen wrapped around the ferrite center 1664. FIG. 19 shows an exampletop view of the ferrite core 1320 when assembled, and FIG. 20 shows aside view of an assembled example core 1320 with an opening 2002 forentry and/or exit of the metallic tube 1340 and/or insulated wire 1330.

The insulated wire 1330 and metallic tube 1340 can be wrapped directlyaround the ferrite center 1664, or may be wrapped around a bobbin 1620inserted into the ferrite core 1320 over the ferrite center 1664.

When arranged in the inductive coil module assembly, an outflow portionof the metallic tube 1340 exiting the inductive coil module assembly1200 can contact an inflow portion of the metallic tube 1340 enteringthe assembly 1200. For example, the outflow portion can be welded to theinflow portion, or the outflow and inflow portions can be wrappedtogether in a heat-shrink encasing. Alternatively, the outflow andinflow portions can pass through an opening into the box that is smallenough to maintain contact between the outflow and inflow portions,without a physical connection between the outflow and inflow portions.

As described above, the ferrite core 1320 can be assembled from multiplepieces 1321 and 1322 of ferrite core. FIG. 21 illustrates incross-section an example of attachment mechanisms facilitating assemblyof the ferrite core 1320. The attachment mechanism can include a tongue1325 and groove 1326 configuration of mating surfaces of the ferritecore 1320 to facilitate mechanical attachment. Tongue 1325 protrusionscan enter and mate with groove 1326 surfaces to align and connect themating ferrite core surfaces. The attaching mechanism can include or usealternatively mechanical detents 1327 that can facilitate mating andlocking the ferrite pieces together.

In addition, the attachment mechanism can include male and femaleconnections of the ferrite core 1320 mating surfaces that mechanicallymeet and contain mechanical detents to physically complete the magneticfield.

In addition, the attachment mechanism can include magnetic componentsthat serve to align and mate the surfaces of the ferrite core pieces tocomplete the magnetic field within the induction coil assembly 1410.Mating magnetic connectors can also be used within a cartridge assemblyto facilitate alignment and connection of the cartridge and the handleof the vapor delivery device.

In addition, the attachment mechanism can include screws and receivinggrooves. Ferrite core pieces can be screwed together with mating pitchthreads and receiving grooves that allow the multiple ferrite pieces tobe assembled together to complete the magnetic field.

In addition, the attachment mechanism can include a bayonetconfiguration. The ferrite core pieces can be placed together, andmounted and locked together, by twisting or rotating the parts inrelation to each other once a mounting piece has entered the receivingreceptacle. As the twist occurs, the ramp within the receptacle canforce the mating ferrite surfaces to complete the magnetic field.

FIG. 22A shows an example configuration of a metallic tube 1340 that canbe used as a heating coil for heating fluid in the vapor deliverydevice. Metallic tube 1340 can have an input end 2202 and output end2204 that are placed onto a fixture 2210. Metallic tube 1340 can bewrapped around pins 2212 on the fixture 2210 in a back and forthfashion. The number of wraps can be determined by the number of pins2212.

FIG. 22B shows the metallic tube 1340 with multiple wraps that can beplaced in a circumferential configuration around a dielectric structure2220. Output end 2204 and input end 2202 can be connectable to ports forfluid flow into the metallic tube 1340 and flow of heated fluid or vaporout of the metallic tube 1340. The axial wrapping configuration shown inFIG. 22B can advantageously extend the amount of time the fluid withinthe metallic tube 1340 can be exposed to heat for vapor production whenthis type of tube configuration is attached to an inductive coilassembly.

Metallic tube 1340 used for a fluid heating coil can be made fromD-shaped tubing, rectangular or square tubing, or tubing with multipletwists in the coil. The metallic tubing 1340 can have varying diametersto increase or decrease fluid or vapor flow within the heating coil, andcan have internal diameter restrictions that also serve to decrease orincrease fluid or vapor flow.

Vapor Delivery Device with Detachable Cartridge Assembly

FIG. 23 shows in cross-section an assembled vapor delivery device 300can be detachably coupled to the cartridge assembly 412 by a tab lock, apush button lock, a spring actuated lock, mechanical detents, magneticcoupling, or a combination thereof. The cartridge assembly 412 can housethe wound Litz wire 432 such that when the cartridge assembly 412 isextended into the proximal opening 422 of the handle 330, the metallictube 440 (e.g., the heating coil) is slid through the induction coilopening 418 and into a lumen of the wound Litz wire 432 within thecartridge assembly 412. The cartridge assembly 412 can also be detachedfrom the handle 330 of the vapor delivery device 300 and the metallictube 440 can be slid out of the lumen of the wound Litz wire 432 and outof the induction coil opening 418.

FIGS. 24 and 25 illustrate that the handle 330 of the vapor deliverydevice 300 can be coupled to the cartridge assembly 412 by a lock tab2400. The lock tab 2400 can have a push button 2402 that actuates aspring 2404 coupled to the push button 2402 shown in FIG. 25. The spring2404 can fit within a slot or opening 2406 along a side of the cartridgeassembly 412 shown in FIG. 26.

The cartridge assembly 412 can comprise a number of connectors,thermocouples, sensors, valves, or a combination thereof. For example,the sensors can include infrared (IR) sensors, intrauterine pressuresensor, or a combination thereof. Also, for example, the valves can bepneumatic valves. The connectors extending from the cartridge assemblycan be male connectors. This allows the cartridge assembly 412 to bemore easily sterilized. The connectors can also be female connectorshaving a removable cap or cover.

FIG. 27 illustrates that the handle 330 can include a non-volatilememory component such as an electrically erasable programmable read-onlymemory (EEPROM) 2710. The EEPROM 2710 can be housed within the handlehousing. The EEPROM 2710 can be positioned above the metallic tube. FIG.27 also illustrates that the cartridge assembly 412 can also one or moreEEPROM controller leads 2712 coupled to a top of the cartridge assembly412. The EEPROM controller leads 2712 can electrically couple with theEEPROM 2710 within the handle 330 when the cartridge assembly 412 isslid into a lumen of the handle 330 and detachably coupled to the handle330 (e.g., via the lock tab mechanism 2400).

FIG. 28 illustrates an example of a cartridge control procedure 2800.The procedure 2800 can involve advancing the cartridge assembly 412 intothe handle 330 in step 2802. The procedure 2800 can also involve theEEPROM 2710 in the handle 330 connecting to the EEPROM controller leads2712 as the cartridge assembly 412 is fully seated or is detachablycoupled to the handle 330 (e.g., via the lock tab mechanism 2400). Forexample, the lock tab mechanism 5002 can be configured such that theEEPROM 2710 is in contact with the EEPROM controller leads 2712 when thelock tab mechanism 500 secures the cartridge assembly 412 to the insideof the handle 330. The procedure 2800 can also involve the controllerchecking to make sure that the EEPROM storage location is empty in step2806. Step 2806 can also involve the controller proceeding withsubsequent steps of the procedure 2800 when the EEPROM storage locationis empty. If the EEPROM storage location is empty, the controller writesto the EEPROM 2710 in step 2808 as each successive step of the procedureis completed (e.g., as the previous step is overwritten). The cartridgecontrol procedure 2800 can ensure that the controller is aware each timethe cartridge assembly 412 is coupled to the handle 330. The cartridgecontrol procedure 2800 also allows the controller to know which step ofthe treatment process has been undertaken by the vapor delivery devicewith a specific cartridge assembly 412 (based on the connection of theEEPROM 2710 in the handle 330 with the EEPROM controller leads 2712 onthe cartridge assembly 412).

Damping Pressure Fluctuations

As described above, pressure in a bodily cavity can fluctuate duringtreatment with the vapor delivery device. For example, intrauterinepressure may be regulated to fall within a range between approximately48 mmHg and 52 mmHg. To dampen the fluctuations of the intrauterinepressure curve and the vapor that exits the induction coil assembly andprior to exiting the vapor delivery device, an output end of the vapordelivery device can contain an additional compliant member that isshaped as a balloon, tubing, or separate compliant chamber that vaporinitially enters the compliant chamber prior to exiting the vapordelivery device and into the uterine cavity.

FIG. 29 illustrates an example system 2900 for damping pressurefluctuations. The system 2900 can include an induction coil assembly1200 with a metallic fluid tube 1340 and a Litz wire 1330. Coupled tothe outflow portion 1344 of the metallic tube 1340 can be a compliantmember 2910 and a chamber 2920. Heated or vaporized fluid can passthrough the compliant member 2910 and chamber 2920 before reaching apatient.

The compliant member 2910 can be made from silicone or other elastomericmaterial that can withstand vapor temperatures. The compliant member2910 can be shaped like a tube or balloon that can expand upon exposureto vapor pressures. The compliance of the compliant member 2910 providedto the vapor exiting the induction coil, and prior to exiting the vapordelivery device and the entering the uterine cavity, can reduce or dampthe fluctuations of vapor pressure that is provided to the uterinecavity.

The complaint chamber 2920 can be a separate compartment or containerfor vapor that can contain an exit regulator 2922 to control or governthe exit of vapor from the induction coil 1200 prior to exiting thevapor delivery device. The chamber 2920 can be a volume betweenapproximately 5 mL and 60 mL, and can have an output 2924 for passingfluid to output channels of the vapor delivery device for delivery to apatient. Fluid exiting the induction coil assembly 1200 may be a mix ofvapor and liquid. Because the liquid has a different viscosity than thevapor, the liquid can cause pressure swings as it passes through outputchannels of the vapor delivery device. As the vapor and heated liquidpass through the chamber 2920, the heavier liquid can fall towards theexit regulator 2922 while the vapor can pass through the chamber outputport 2924. The fluid beyond the chamber output port 2924 may thereforehave a higher vapor quality than fluid entering the chamber 2920. Thechamber 2920 may additionally have compliant walls to further damppressure variations.

FIGS. 30A and 30B illustrate examples of the chamber 2920. The exitregulator 2922 can allow collected liquid to exit the chamber 2920. Theexit regulator 2922 can be a flow restrictor allowing liquid to drainfrom the chamber 2920 at a specified rate. For example, the flowrestrictor can be designed to drain liquid at approximately a rate atwhich the liquid is expected to collect in the chamber 2920. The exitregulator 2922 can alternatively comprise a valve that can be opened atperiodic intervals to drain the collected liquid from the chamber 2920.The valve can open automatically at a specified pressure (e.g., when aspecified volume of liquid has collected in the chamber 2920). The valvecan alternatively be controlled pneumatically or electronically to openat a specified interval of time, or when a pressure sensor detects aspecified pressure in the chamber 2920. An absorbent member can beplaced in the chamber 2920 in addition to or instead of the exitregulator 2922.

As stated herein, the induction coil vapor generator can include awrapping of Litz wire, insulated wire, or coiled magnet wire 102 whichin this embodiment is supported by an outer assembly 104, and an innerassembly 106 disposed within the outer assembly. The induction coil 100contains lumens, tubes, cavities, or metallic microtubes 108 disposedwithin the inner assembly 104. The tubes can be coupled to a fluidsource 118 that supplies saline, water, distilled water, or other fluidthat will be heated or converted into steam or vapor. In someembodiments, the outer assembly can comprise an electrically insulatingand thermally insulating material, such as aerogel, foam, fiberglass, orlow density silicone. To further provide insulation, the outer assemblycan contain air gaps. The outer assembly can be thermally insulating toprevent heat from damaging the coiled magnet wire during the treatmentcycle. Since the Litz wire or insulated wire can become excessivelyheated, the insulation is designed to prevent heat from engaging thepatient or the operator. The excessive heat can also damage othermedical device components in close proximity to the inductive coil. Theinner assembly can comprise an electrically insulating, thermallyconductive material, such as aluminum nitride, alloys of iron includingstainless steels, alloys of nickel including ferrite, alloys of cobalt,quartz, glass, or a ceramic such as aluminum oxide. The inner assemblyand the tubes contained within or in close proximity can be thermallyconductive so as to inductively heat the fluid supplied by the fluidsource 118. For the application of uterine endometrial ablation, thefluid is converted into vapor that can be delivered into the uterinecavity.

The Litz or insulated wire 102 can comprise any electrically insulatedwire, such as insulated copper, silver, gold or aluminum wire used inelectromagnets (magnet wire).

The device can have only one metallic tube that is formed and wrappedaround the inner assembly. Having only one metallic tube can expose thefluid for a greater time duration within the heated inductive field andimproves the vapor output of the assembly. The metallic tube can wraparound as a coil and can also be referred to as the “heating coil” inwhich fluid within the metallic tube is heated and converted to vapor.

The cartridge assembly 412 can contain no fluid pathways that deliverfluid or vapor to the patient which can further allow it to be areusable component for cost savings purposes. The vapor delivery device300 can contain the fluid conduit which threads through the handle andinto the metallic tube, also called the heating coil. Fluid can beconverted into vapor in the metallic tube once it is heated and providesvapor into the vapor input port which ultimately delivers the vapor tothe uterine cavity through distal end. The vapor delivery device 300 cancontain an intrauterine pressure sensor 451 located near the distal tipand sealing balloons 452 located in the position to interact with theendocervical canal once inserted within the patient.

The distal opening of the cartridge assembly can be positioned fullyinto the handle and the induction coil can be now fully assembled withinsulated or Litz wire visible with heating coil or metallic tube. Thephysician can assemble the vapor delivery device 300 by inserting thecartridge assembly within the handle.

Monitoring for drops in intrauterine pressure, or rapid changes in vaporflow, may be incorporated into the software and hardware regulationsystem. For cervical seal failures, additional safety mechanisms such asthermocouples located in the cervix region can be utilized.

Vapor treatment (e.g., with shorter time durations than two minutes) canbe used for small tumors, polyps, lungs, varicose veins, and smallerlumens, ducts, and bodily cavities.

The cartridge assembly's connector(s) can contain an inflow conduit andan outflow conduit, for example, to allow a flow of air to cool theinductive coil assembly.

As for additional details pertinent to the present disclosure, materialsand manufacturing techniques may be employed as within the level ofthose with skill in the relevant art. The same may hold true withrespect to method-based aspects of the disclosure in terms of additionalacts commonly or logically employed. Also, it is contemplated that anyoptional feature of the variations described herein may be set forth andclaimed independently, or in combination with any one or more of thefeatures described herein. Likewise, reference to a singular itemincludes the possibility that there are plural of the same itemspresent. More specifically, as used herein and in the appended claims,the singular forms “a,” “and,” “said,” and “the” include pluralreferents unless the context clearly dictates otherwise. It is furthernoted that the claims may be drafted to exclude any optional element. Assuch, this statement is intended to serve as antecedent basis for use ofsuch exclusive terminology as “solely,” “only” and the like inconnection with the recitation of claim elements, or use of a “negative”limitation. Unless defined otherwise herein, all technical andscientific terms used herein have the same meaning as commonlyunderstood by one of ordinary skill in the art to which this disclosurebelongs. The breadth of the present disclosure is not to be limited bythe subject specification, but rather only by the plain meaning of theclaim terms employed.

We claim:
 1. An induction coil system, comprising: a closed loop ferritecore; a wire configured to carry electric current coiled around a firstportion of the closed loop ferrite core and at least partiallysurrounded by the closed loop ferrite core; and a fluid tube configuredto carry a fluid coiled around a second portion of the closed loopferrite core and at least partially surrounded by the closed loopferrite core; wherein the electric current in the wire generates amagnetizing inductance to inductively heat the fluid tube.
 2. Theinduction coil system of claim 1, wherein the closed loop ferrite corecomprises a ferrite side, a ferrite top, a ferrite bottom, and a ferritecenter.
 3. The induction coil system of claim 2, wherein the wire andthe fluid tube are coiled around the ferrite center.
 4. The inductioncoil system of claim 2, wherein the closed loop ferrite core furthercomprises a ferrite back.
 5. The induction coil system of claim 1,wherein a coil of the fluid tube around the second portion of the closedloop ferrite core comprises a wrap of less than 360 degrees around thesecond portion of the closed loop ferrite core.
 6. The induction coilsystem of claim 1, wherein a coil of the fluid tube around the secondportion of the closed loop ferrite core comprises one or more 360-degreewraps around the second portion of the closed loop ferrite core.
 7. Theinduction coil system of claim 1, wherein the wire when coiled aroundthe first portion of the closed loop ferrite core at least partiallyoverlaps the fluid tube when coiled around the second portion of theclosed loop ferrite core.
 8. An induction coil system, comprising: aclosed loop ferrite core comprising: a ferrite frame comprising aferrite side, a ferrite top, a ferrite bottom; and a ferrite centerwithin the ferrite frame between the ferrite top and the ferrite bottom;a wire configured to carry electric current coiled around a firstportion of the ferrite center; and a fluid tube configured to carry afluid coiled around a second portion of the ferrite center; wherein theelectric current in the wire generates a magnetizing inductance toinductively heat the fluid tube.
 9. The induction coil system of claim8, wherein the closed loop ferrite core further comprises a ferriteback.
 10. The induction coil system of claim 8, wherein a coil of thefluid tube comprises a wrap of less than 360 degrees around the secondportion of the ferrite center.
 11. The induction coil system of claim 8,wherein a coil of the fluid tube comprises one or more 360-degree wrapsaround the second portion of the ferrite center.
 12. The induction coilsystem of claim 8, wherein the wire when coiled around the first portionof the ferrite center at least partially overlaps the fluid tube whencoiled around the second portion of the ferrite center.
 13. Theinduction coil system of claim 8, wherein the wire is between the fluidtube and the ferrite center.
 14. The induction coil system of claim 8,further comprising a bobbin including an electrically insulatingmaterial, wherein the bobbin is concentric to the ferrite center andwherein the wire and fluid tube are each coiled around the bobbin. 15.An induction coil system, comprising: a closed loop ferrite corecomprising a ferrite side, a ferrite top, a ferrite bottom, and aferrite center between the ferrite top and the ferrite bottom; a wireconfigured to carry electric current coiled around a first portion ofthe ferrite center; and a fluid tube configured to carry a fluid coiledaround a second portion of the ferrite center, wherein: the electriccurrent in the wire generates a magnetizing inductance to inductivelyheat the fluid tube; and the wire is between the fluid tube and theferrite center.
 16. The induction coil system of claim 8, wherein theferrite side, the ferrite top, and the ferrite bottom are eachsubstantially rectangular.